PORTLAND — Pauli Daniels has been prescribed drugs that she no longer uses or aren’t on the market anymore.

Daniels, who lives on Portland’s Eastern Promenade, didn’t want to flush them down the toilet into the city’s waterways or let them get into the wrong hands.

“I don’t want them hanging around the house,” she said. “I have grandchildren.”

Daniels’ dilemma was solved Saturday, when the U.S. Drug Enforcement Agency held its third National Prescription Drug Take Back Day since 2010.

At pharmacies, in parking lots and at police stations nationwide, unwanted drugs were discarded in drop boxes monitored by police.

Although flushing pills was once an accepted way to dispose of them, environmental concerns about the practice have arisen.

The main reason of the DEA’s program, however, is to keep the pills away from people who might abuse them. MaineToday Media recently published a six-part series about the prevalence of painkiller addiction in the state.

Daniels took a plastic bag of pills to the Rite Aid pharmacy at 290 Congress St., where Portland police Sgt. Charles Libby was stationed by a cardboard box in the parking lot.

In about three hours, he said, 20 to 30 people had stopped to drop off their drugs.

One had a full trash bag, some had just a couple of bottles, and rest came with “everything in between,” Libby said.

Another Rite Aid on Congress Street also was collecting pills Saturday, as was the University of New England College of Pharmacy on Stevens Avenue.

About a dozen pharmacy students volunteered to collect and count the pills. They looked at the prescriptions on the bottles and recorded how many pills patients were given and how many they took. They’ll enter the numbers into a national data system for a study on prescription drug waste.

Alexandra Malinowski, a second-year pharmacy student, said the study’s purpose is to generate funding for more safe drug disposal efforts like Saturday’s collection.

The discarded pills had the pharmacy students hard at work at laboratory benches, where they poured out the bottles and made notes about the medications.

“Clearly, there’s a lot of waste,” Malinowski said.